EP0419842A1 - Method for removing halogenated organic contaminants with at least 5 C-atoms from water - Google Patents
Method for removing halogenated organic contaminants with at least 5 C-atoms from water Download PDFInfo
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- EP0419842A1 EP0419842A1 EP90116049A EP90116049A EP0419842A1 EP 0419842 A1 EP0419842 A1 EP 0419842A1 EP 90116049 A EP90116049 A EP 90116049A EP 90116049 A EP90116049 A EP 90116049A EP 0419842 A1 EP0419842 A1 EP 0419842A1
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- water
- iron
- pollutants
- oxidizing agent
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- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 title claims abstract description 50
- 238000000034 method Methods 0.000 title claims abstract description 30
- 125000004432 carbon atom Chemical group C* 0.000 title claims abstract description 15
- 239000000356 contaminant Substances 0.000 title abstract 4
- VTLYFUHAOXGGBS-UHFFFAOYSA-N Fe3+ Chemical compound [Fe+3] VTLYFUHAOXGGBS-UHFFFAOYSA-N 0.000 claims abstract description 26
- 239000007800 oxidant agent Substances 0.000 claims abstract description 20
- MHAJPDPJQMAIIY-UHFFFAOYSA-N Hydrogen peroxide Chemical compound OO MHAJPDPJQMAIIY-UHFFFAOYSA-N 0.000 claims abstract description 19
- CWYNVVGOOAEACU-UHFFFAOYSA-N Fe2+ Chemical compound [Fe+2] CWYNVVGOOAEACU-UHFFFAOYSA-N 0.000 claims description 45
- 239000003344 environmental pollutant Substances 0.000 claims description 27
- 231100000719 pollutant Toxicity 0.000 claims description 27
- 229910052736 halogen Inorganic materials 0.000 claims description 13
- 150000002367 halogens Chemical class 0.000 claims description 13
- 238000001179 sorption measurement Methods 0.000 claims description 10
- 230000003647 oxidation Effects 0.000 claims description 9
- 238000007254 oxidation reaction Methods 0.000 claims description 9
- 238000000926 separation method Methods 0.000 claims description 9
- 239000000149 chemical water pollutant Substances 0.000 claims description 8
- 239000003673 groundwater Substances 0.000 claims description 7
- 150000004826 dibenzofurans Chemical class 0.000 claims description 4
- 231100001240 inorganic pollutant Toxicity 0.000 claims description 4
- 239000007864 aqueous solution Substances 0.000 claims description 3
- 150000001616 biphenylenes Chemical class 0.000 claims description 3
- 230000007062 hydrolysis Effects 0.000 claims description 3
- 238000006460 hydrolysis reaction Methods 0.000 claims description 3
- VGVRPFIJEJYOFN-UHFFFAOYSA-N 2,3,4,6-tetrachlorophenol Chemical class OC1=C(Cl)C=C(Cl)C(Cl)=C1Cl VGVRPFIJEJYOFN-UHFFFAOYSA-N 0.000 claims description 2
- 150000001555 benzenes Chemical class 0.000 claims description 2
- 150000002927 oxygen compounds Chemical class 0.000 claims description 2
- JRKICGRDRMAZLK-UHFFFAOYSA-L persulfate group Chemical group S(=O)(=O)([O-])OOS(=O)(=O)[O-] JRKICGRDRMAZLK-UHFFFAOYSA-L 0.000 claims description 2
- 239000000575 pesticide Substances 0.000 claims description 2
- 239000012266 salt solution Substances 0.000 claims description 2
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 claims 2
- 229910052697 platinum Inorganic materials 0.000 claims 1
- XEEYBQQBJWHFJM-UHFFFAOYSA-N iron Substances [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 abstract description 11
- 150000003839 salts Chemical class 0.000 abstract 1
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 12
- 239000002957 persistent organic pollutant Substances 0.000 description 11
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 9
- -1 Fe2+ ions Chemical class 0.000 description 6
- 238000001556 precipitation Methods 0.000 description 6
- 239000002351 wastewater Substances 0.000 description 6
- 239000000460 chlorine Substances 0.000 description 5
- 238000005189 flocculation Methods 0.000 description 5
- 230000016615 flocculation Effects 0.000 description 5
- 239000000126 substance Substances 0.000 description 5
- ZAMOUSCENKQFHK-UHFFFAOYSA-N Chlorine atom Chemical compound [Cl] ZAMOUSCENKQFHK-UHFFFAOYSA-N 0.000 description 4
- 229910052801 chlorine Inorganic materials 0.000 description 4
- 238000011065 in-situ storage Methods 0.000 description 4
- 239000000203 mixture Substances 0.000 description 4
- 239000002244 precipitate Substances 0.000 description 4
- 239000000243 solution Substances 0.000 description 4
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 3
- 150000001875 compounds Chemical class 0.000 description 3
- 239000001301 oxygen Substances 0.000 description 3
- 229910052760 oxygen Inorganic materials 0.000 description 3
- 239000012071 phase Substances 0.000 description 3
- 239000012028 Fenton's reagent Substances 0.000 description 2
- 229910021577 Iron(II) chloride Inorganic materials 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- OSVXSBDYLRYLIG-UHFFFAOYSA-N dioxidochlorine(.) Chemical compound O=Cl=O OSVXSBDYLRYLIG-UHFFFAOYSA-N 0.000 description 2
- 238000000605 extraction Methods 0.000 description 2
- 239000000706 filtrate Substances 0.000 description 2
- MGZTXXNFBIUONY-UHFFFAOYSA-N hydrogen peroxide;iron(2+);sulfuric acid Chemical compound [Fe+2].OO.OS(O)(=O)=O MGZTXXNFBIUONY-UHFFFAOYSA-N 0.000 description 2
- WQYVRQLZKVEZGA-UHFFFAOYSA-N hypochlorite Chemical compound Cl[O-] WQYVRQLZKVEZGA-UHFFFAOYSA-N 0.000 description 2
- 239000004615 ingredient Substances 0.000 description 2
- NMCUIPGRVMDVDB-UHFFFAOYSA-L iron dichloride Chemical compound Cl[Fe]Cl NMCUIPGRVMDVDB-UHFFFAOYSA-L 0.000 description 2
- RBTARNINKXHZNM-UHFFFAOYSA-K iron trichloride Chemical compound Cl[Fe](Cl)Cl RBTARNINKXHZNM-UHFFFAOYSA-K 0.000 description 2
- BAUYGSIQEAFULO-UHFFFAOYSA-L iron(2+) sulfate (anhydrous) Chemical compound [Fe+2].[O-]S([O-])(=O)=O BAUYGSIQEAFULO-UHFFFAOYSA-L 0.000 description 2
- QGPQTSCLUYMZHL-UHFFFAOYSA-N iron(3+);oxygen(2-);hydrate Chemical compound O.[O-2].[O-2].[O-2].[Fe+3].[Fe+3] QGPQTSCLUYMZHL-UHFFFAOYSA-N 0.000 description 2
- 229910000359 iron(II) sulfate Inorganic materials 0.000 description 2
- 238000000622 liquid--liquid extraction Methods 0.000 description 2
- 150000004045 organic chlorine compounds Chemical class 0.000 description 2
- 230000001590 oxidative effect Effects 0.000 description 2
- 238000000746 purification Methods 0.000 description 2
- 239000010802 sludge Substances 0.000 description 2
- 238000000638 solvent extraction Methods 0.000 description 2
- 239000004155 Chlorine dioxide Substances 0.000 description 1
- DGAQECJNVWCQMB-PUAWFVPOSA-M Ilexoside XXIX Chemical compound C[C@@H]1CC[C@@]2(CC[C@@]3(C(=CC[C@H]4[C@]3(CC[C@@H]5[C@@]4(CC[C@@H](C5(C)C)OS(=O)(=O)[O-])C)C)[C@@H]2[C@]1(C)O)C)C(=O)O[C@H]6[C@@H]([C@H]([C@@H]([C@H](O6)CO)O)O)O.[Na+] DGAQECJNVWCQMB-PUAWFVPOSA-M 0.000 description 1
- 229910021578 Iron(III) chloride Inorganic materials 0.000 description 1
- 238000010521 absorption reaction Methods 0.000 description 1
- 230000002378 acidificating effect Effects 0.000 description 1
- 125000001931 aliphatic group Chemical group 0.000 description 1
- 239000003513 alkali Substances 0.000 description 1
- 150000001336 alkenes Chemical class 0.000 description 1
- 150000001350 alkyl halides Chemical class 0.000 description 1
- 239000008346 aqueous phase Substances 0.000 description 1
- 150000001491 aromatic compounds Chemical class 0.000 description 1
- 125000003118 aryl group Chemical group 0.000 description 1
- 230000003139 buffering effect Effects 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 230000003197 catalytic effect Effects 0.000 description 1
- 238000001311 chemical methods and process Methods 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 150000008280 chlorinated hydrocarbons Chemical class 0.000 description 1
- 235000019398 chlorine dioxide Nutrition 0.000 description 1
- 238000002485 combustion reaction Methods 0.000 description 1
- 238000011109 contamination Methods 0.000 description 1
- 238000010924 continuous production Methods 0.000 description 1
- 230000006735 deficit Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 150000002013 dioxins Chemical class 0.000 description 1
- VTIIJXUACCWYHX-UHFFFAOYSA-L disodium;carboxylatooxy carbonate Chemical compound [Na+].[Na+].[O-]C(=O)OOC([O-])=O VTIIJXUACCWYHX-UHFFFAOYSA-L 0.000 description 1
- 239000003651 drinking water Substances 0.000 description 1
- 235000020188 drinking water Nutrition 0.000 description 1
- 239000000839 emulsion Substances 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000001704 evaporation Methods 0.000 description 1
- 230000008020 evaporation Effects 0.000 description 1
- 150000002240 furans Chemical class 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 230000005484 gravity Effects 0.000 description 1
- 150000008282 halocarbons Chemical class 0.000 description 1
- 229910001385 heavy metal Inorganic materials 0.000 description 1
- 150000002390 heteroarenes Chemical class 0.000 description 1
- 125000001072 heteroaryl group Chemical group 0.000 description 1
- 229910052945 inorganic sulfide Inorganic materials 0.000 description 1
- 229910052742 iron Inorganic materials 0.000 description 1
- 229910000360 iron(III) sulfate Inorganic materials 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 150000002825 nitriles Chemical class 0.000 description 1
- 229910000510 noble metal Inorganic materials 0.000 description 1
- 150000002896 organic halogen compounds Chemical class 0.000 description 1
- 238000006385 ozonation reaction Methods 0.000 description 1
- 238000010979 pH adjustment Methods 0.000 description 1
- 150000004968 peroxymonosulfuric acids Chemical class 0.000 description 1
- 150000003071 polychlorinated biphenyls Chemical class 0.000 description 1
- 239000000047 product Substances 0.000 description 1
- 230000035484 reaction time Effects 0.000 description 1
- 238000009938 salting Methods 0.000 description 1
- 239000010865 sewage Substances 0.000 description 1
- 229910052708 sodium Inorganic materials 0.000 description 1
- 239000011734 sodium Substances 0.000 description 1
- 229940045872 sodium percarbonate Drugs 0.000 description 1
- 239000002904 solvent Substances 0.000 description 1
- 238000003756 stirring Methods 0.000 description 1
- LSNNMFCWUKXFEE-UHFFFAOYSA-L sulfite Chemical class [O-]S([O-])=O LSNNMFCWUKXFEE-UHFFFAOYSA-L 0.000 description 1
- 239000002562 thickening agent Substances 0.000 description 1
- 230000002110 toxicologic effect Effects 0.000 description 1
- 231100000027 toxicology Toxicity 0.000 description 1
- 239000002699 waste material Substances 0.000 description 1
- 239000003643 water by type Substances 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/72—Treatment of water, waste water, or sewage by oxidation
- C02F1/722—Oxidation by peroxides
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/52—Treatment of water, waste water, or sewage by flocculation or precipitation of suspended impurities
- C02F1/5236—Treatment of water, waste water, or sewage by flocculation or precipitation of suspended impurities using inorganic agents
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2103/00—Nature of the water, waste water, sewage or sludge to be treated
- C02F2103/06—Contaminated groundwater or leachate
Definitions
- the invention relates to a process for the separation of organohalogen pollutants with at least 5 carbon atoms from water, in particular wastewater, to residual values below 1 mg / l, calculated as organically bound halogen, preferably below 0.2 mg / l.
- the process has one stage and is based on the oxidation of Fe2+ ions present and / or added in water to Fe3+ ions and the precipitation of iron (III) -hydroxo complexes, on which the halogen-organic pollutants are adsorbed and separated with them.
- the process is preferably controlled electrometrically and is particularly suitable for the separation of perchlorinated biphenylenes (PCB's), perchlorinated dibenzodioxins and dibenzofurans as well as other halogenated aromatics and heteroaromatics and longer-chain halogenated hydrocarbons.
- PCB's perchlorinated biphenylenes
- dibenzodioxins and dibenzofurans as well as other halogenated aromatics and heteroaromatics and longer-chain halogenated hydrocarbons.
- organochlorine compounds can be separated from an aqueous phase, but complete separation is only ensured by a four-step extraction.
- Another disadvantage is that, especially in the case of leachate, a strong emulsion formation occurs and an adsorption step has to be carried out after the extraction.
- the object of the invention is to provide a process for the separation of organohalogen pollutants with at least 5 carbon atoms from water, which may additionally contain other organic and / or inorganic pollutants, which allows the aforementioned organohalogen pollutants to be controlled in a simple and easy manner Separate adsorption on in situ formed iron (III) hydroxo complexes down to residual values of less than 1 mg / l, calculated as organically bound halogen.
- the process should be able to be operated reliably with the lowest possible use of chemicals and a low amount of contaminated products even if the content of pollutants in the water to be treated fluctuates greatly.
- the object is achieved by a process for separating organohalogen pollutants with at least 5 carbon atoms from water, which may additionally contain other organic and / or inorganic pollutants, to residual values below 1 mg / l, calculated as organically bound halogen, by adsorption of the organohalogen pollutants on iron (III) hydroxo complexes formed in situ by hydrolysis of iron (III) salts and separation thereof in flocculent form at pH 5 to 10, which is characterized in that the Fe2+ content in the water is determined and if necessary, by adding an iron (II) salt to a content of 20 to 1000 mg Fe2+ per l of water and then adding an oxidizing agent for converting Fe2+ in Fe3+ in an amount that does not exceed those for oxidation of at least 20 mg Fe2+ / l and a maximum of 1000 mg of the amount Fe2+ / l present in the presence of any present, such as Fe2+ practically instantaneously Lich oxidizable other ingredients is required.
- the water to be treated according to the invention can be water of different provenances, for example process water, waste water or, particularly preferably, landfill leachate and contaminated groundwater. After treatment, the water can, if necessary, be sent to a biological treatment plant.
- the halogen-organic pollutants to be separated with at least 5 C atoms are in particular those from the group of polychlorinated biphenylenes (PCB's), polychlorinated dibenzodioxins and dibenzofurans, polychlorinated benzenes, chlorophenols, halogen-containing pesticides and aliphatic and cycloaliphatic chlorinated hydrocarbons with at least 5 C atoms .
- PCB's polychlorinated biphenylenes
- the process is particularly suitable for separating the so-called PCBs, including the above-mentioned dioxins and furans and aromatic compounds.
- the residual value of less than 1 mg / l refers to the organically bound chlorine of the halogen-organic pollutants with more than 5 carbon atoms.
- Organohalogen compounds with 1 to 4 carbon atoms such as haloalkanes and alkenes, are not or only incompletely separated from the water in the process according to the invention.
- the process according to the invention can thus be used particularly advantageously where the water contains no halogen-organic pollutants with 1 to 4 carbon atoms or where it is not necessary to separate them.
- the process according to the invention is preferably operated such that the residual content of organically bound chlorine in the absence of organo-halogenated C1-C4 compounds in the water to be treated is below 0.2 mg / l and particularly preferably below 0.1 mg / l.
- Flocculation or precipitation of iron (III) -hydroxo complexes formed in situ by hydrolysis of iron (III) compounds which allows colloidal and to a varying extent dissolved components in water to be separated off by adsorption and / or inclusion, is in wastewater technology a well-known and also practiced process step.
- a soluble iron (III) compound is usually added to the water, and above a pH of about 3.5 the precipitation begins, which is practically quantitative at pH 5.
- a pH value above 7 is often set in order to form a precipitation that is easier to separate and drain by gravity. It was found that the flocculation to a certain extent enables the pollutants claimed to be separated off, but that residual values below 1 mg / l of organically bound halogen cannot be achieved with them.
- the water to be treated should contain 20 to 1000 mg Fe2 mg / l, preferably 50 to 500 mg / g and particularly preferably 100 to 200 mg / g.
- This Fe2+ content can be present in whole or in part in the water to be treated or can be adjusted by adding a soluble iron (II) compound, preferably FeSO4 ⁇ 7 H2O or FeCl2.
- a soluble iron (II) compound preferably FeSO4 ⁇ 7 H2O or FeCl2.
- the FeCl2 content can also be over 1000 mg / l, but this is less recommendable in view of the resulting sludge volume and is not necessary for the purpose of separating the halogen-organic pollutants.
- a sufficient amount of oxidizing agent is added to the water containing Fe2+ for the oxidation of Fe2+ to Fe3+. It is a characteristic of the process that the amount of oxidizing agent is dimensioned so that at least 20 mg Fe2+ / l up to a maximum of the amount of Fe2+ / l present, i.e. a maximum of 1000 mg Fe2+ / l, in the presence of any present, such as Fe2+ can be oxidized practically instantaneously oxidizable other organic and / or inorganic ingredients of the water to be treated. Preferably, essentially the entire amount of Fe2+ present is oxidized. There is therefore no oxidizing agent available for the oxidative attack of carbon atoms.
- Oxygen as an oxidizing agent has the disadvantage that it can lead to considerable odor emissions when treating heavily contaminated water, such as landfill leachate. Ozonation is possible, but is usually not very economical.
- Active oxygen compounds such as in particular hydrogen peroxide, persulfuric acid, persulfates, sodium percarbonate, sodium perborates. Hydrogen peroxide is very particularly preferred in the form of commercially available aqueous solutions with a content of 30-85% by weight, if desired, solutions which are more dilute than 30% by weight can also be used.
- the inventive method can be controlled very easily by measuring the Fe2+ / Fe3+ redox potential.
- the Fe2+ / Fe3+ redox potential which z. B. using a noble metal electrode and a reference electrode, can be used to determine both the Fe2+ content and the dosage of the oxidizing agent, since with complete conversion of Fe2+ to Fe3+ a practically constant potential value of +970 to + 980 mV (Pt / thalamide electrode chain) is reached.
- a potential of +450 mV corresponds to approximately 1000 mg Fe2+ / l and a potential value of +600 mV corresponds to approximately 70 mg Fe2+ / l - measured at pH 7.2.
- the dosing pump for the oxidizing agent is automatically switched off when the specified end potential value is reached.
- the pH of the water to be treated can initially be in the slightly acidic to weakly alkaline range, about pH 5-9. During the oxidation, the pH value drops depending on the Fe2+ content and the buffering capacity of the water. If the pH value drops below 5 after the addition of the oxidizing agent, the precipitation of Fe (III) - which usually begins during the addition of the oxidizing agent - hydroxo complexes completed by the subsequent addition of an alkaline alkali or alkaline earth compound.
- the precipitate containing the adsorbed halogenated and possibly other pollutants is separated from the water at pH 5-10, preferably 7.5-9.
- Common devices such as thickeners, separators, centrifuges, filter presses can be used for the separation.
- the separated precipitate, which contains the pollutants can be fed to an incineration plant.
- Landfill leachate and groundwater usually occur in a pH range of 6.5 to 7.5. At this pH, the Fe2 gel dissolved or added therein is in dissolved form, so that the concentration can be determined as a function of the measured redox potential using a previously created diagram.
Landscapes
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Engineering & Computer Science (AREA)
- Environmental & Geological Engineering (AREA)
- Water Supply & Treatment (AREA)
- Hydrology & Water Resources (AREA)
- Life Sciences & Earth Sciences (AREA)
- Inorganic Chemistry (AREA)
- Treatment Of Water By Oxidation Or Reduction (AREA)
- Water Treatment By Sorption (AREA)
- Solid-Sorbent Or Filter-Aiding Compositions (AREA)
- Extraction Or Liquid Replacement (AREA)
- Removal Of Specific Substances (AREA)
Abstract
Description
Die Erfindung betrifft ein Verfahren zur Abtrennung von halogenorganischen Schadstoffen mit mindestens 5 C-Atomen aus Wasser, insbesondere Abwasser, auf Restwerte unter 1 mg/l, berechnet als organisch gebundenes Halogen, vorzugsweise unter 0,2 mg/l. Das Verfahren ist einstufig und basiert auf der Oxidation von im Wasser vorhandenen und/oder zugegebenen Fe²⁺-Ionen zu Fe³⁺-Ionen und Ausfällung von Eisen(III)-hydroxokomplexen, an welchen die halogenorganischen Schadstoffe adsorbiert und mit diesen abgetrennt werden. Das Verfahren wird vorzugsweise elektrometrisch gesteuert und eignet sich insbesondere zur Abtrennung von perchlorierten Biphenylenen (PCB's), perchlorierten Dibenzodioxinen und Dibenzofuranen sowie anderen halogenierten Aromaten und Heteroaromaten und längerkettigen Halogenkohlenwasserstoffen.The invention relates to a process for the separation of organohalogen pollutants with at least 5 carbon atoms from water, in particular wastewater, to residual values below 1 mg / l, calculated as organically bound halogen, preferably below 0.2 mg / l. The process has one stage and is based on the oxidation of Fe²⁺ ions present and / or added in water to Fe³⁺ ions and the precipitation of iron (III) -hydroxo complexes, on which the halogen-organic pollutants are adsorbed and separated with them. The process is preferably controlled electrometrically and is particularly suitable for the separation of perchlorinated biphenylenes (PCB's), perchlorinated dibenzodioxins and dibenzofurans as well as other halogenated aromatics and heteroaromatics and longer-chain halogenated hydrocarbons.
Die Abtrennung von halogenorganischen Schadstoffen aus Wasser, insbesondere Abwasser, gewinnt aus toxikologischen und ökotoxikologischen Gründen an Bedeutung. So ist eine Behandlung von zum Beispiel Sickerwässern aus Deponien sowie mit halogenorganischen Schadstoffen belasteter Grundwässer erforderlich. Einerseits würden Deponiesickerwässer, wenn sie ohne Vorbehandlung in einen Vorfluten gelangen, zu starken Beeinträchtigungen von Fauna und Flora führen und bei Einleitung in eine biologische Kläranlage deren Betrieb empfindlich stören oder gar verhindern. Andererseits würde ein Versickern im Erdreich zu einer Verseuchung des Grundwassers führen, was dessen Verwendung zur Gewinnung von Trinkwasser verhindern würde. Die Behandlung von mit halogenorganischen Schadstoffen kontaminiertem Grundwasser ist erforderlich, um dessen Ausbreitung zu verhindern.The separation of organohalogen pollutants from water, especially wastewater, is becoming increasingly important for toxicological and ecotoxicological reasons. For example, treatment of leachate from landfills and groundwater contaminated with halogen organic pollutants is required. On the one hand, landfill leachate, if it gets into a pre-flooding without pretreatment, would lead to severe impairment of fauna and flora and, if discharged into a biological sewage treatment plant, would seriously impair or even prevent its operation. On the other hand, seepage in the ground would lead to contamination of the groundwater, which would prevent its use for the production of drinking water. The treatment of groundwater contaminated with organic halogen pollutants is necessary to prevent its spread.
Für die Behandlung von halogenorganische Schadstoffe enthaltenden Sicker- und Grundwässern, welche im allgemeinen in mehr oder weniger großer Menge zusätzlich andere organische und anorganische Schadstoffe enthalten, stehen derzeit die folgenden physikalisch-chemischen Verfahren zur Verfügung - siehe K. Leonhard in "Berichte aus Wassergütewirtschaft und Gesundheitsingenieurwesen der Technischen Universität München" Nr. 74 (1987), 230-237: Flüssig-Flüssig-Extraktion, Strippung mit Dampf und Luft, Mono- oder Bidestillation, Adsorption an Aktivkohle.The following physico-chemical processes are currently available for the treatment of leachate and groundwater containing halogen organic pollutants, which generally also contain other organic and inorganic pollutants in more or less large quantities - see K. Leonhard in "Reports from water quality management and Health engineering of the Technical University of Munich "No. 74 (1987), 230-237: liquid-liquid extraction, stripping with steam and air, mono or bidistillation, adsorption on activated carbon.
Aufgrund der komplexen Zusammensetzung der infragestehenden Wässer ist eine vollständige Entfernung der eine biologische Reinigungsstufe störenden Schadstoffe im allgemeinen nur durch eine Kombination verschiedener und/oder mehrstufiger Verfahren möglich. Dies bedingt einen erheblichen Aufwand bei der Einstellung und dem Betrieb dafür geeigneter Anlagen. Wegen der z. T. rasch wechselnden Zusammensetzung der Wässer sind solche Verfahren von besonderem Interesse, welche bei kontinuierlichem Betrieb sicher steuerbar und damit wirtschaftlich zu betreiben sind.Due to the complex composition of the water in question, a complete removal of the pollutants which interfere with a biological purification stage is generally only possible by a combination of different and / or multi-stage processes. This requires considerable effort when setting up and operating suitable systems. Because of the z. T. rapidly changing composition of the waters are of particular interest those processes which can be safely controlled during continuous operation and are therefore economical to operate.
Mit einer Flüssig-Flüssig-Extraktion können zwar chlororganische Verbindungen aus einer wäßrigen Phase abgetrennt werden, jedoch wird eine vollständige Abtrennung nur durch eine vierstufige Extraktion sichergestellt. Nachteilig ist ferner, daß gerade bei Sickerwässern eine starke Emulsionsbildung auftritt und ein Adsorptionsschritt der Extraktion nachgeschaltet werden muß.With a liquid-liquid extraction, organochlorine compounds can be separated from an aqueous phase, but complete separation is only ensured by a four-step extraction. Another disadvantage is that, especially in the case of leachate, a strong emulsion formation occurs and an adsorption step has to be carried out after the extraction.
Durch Strippung von halogenorganischen Schadstoffen mit Dampf oder Luft verteilen sich die Schadstoffe sowohl auf die Strippphase als auch die eigentliche Wasserphase, so daß aus beiden Phasen durch weitere Verfahren, etwa Adsorption oder Verbrennung, die jeweils darin enthaltenen halogenorganischen Schadstoffe entfernt werden müssen.By stripping organic halogen pollutants with steam or air, the pollutants are distributed over both the stripping phase and the actual water phase, so that the halogen organic pollutants contained therein must be removed from both phases by further processes, such as adsorption or combustion.
Die Eindampfverfahren sind einmal sehr energieaufwendig, zum anderen können mit den Brüden halogenorganische Schadstoffe, sogar perchlorierte Dibenzodioxine und Dibenzofurane, abgetrieben werden, so daß andere Verfahren, etwa eine Adsorption an Aktivkohle, nachgeschaltet werden müssen.The evaporation process is very energy-intensive on the one hand, and on the other hand, organic vapors, even perchlorinated dibenzodioxins and dibenzofurans, can be driven off with the vapors, so that other processes, such as adsorption on activated carbon, have to be followed.
Die Adsorption von in hochbelasteten Abwässern oder Sickerwässern enthaltenen aromatischen, heteroaromatischen und aliphatischen Halogenverbindungen an Aktivkohle kann nur als Nachbehandlungsstufe angesehen werden, da der direkte Einsatz eine extrem hohe Einsatzmenge und zusätzlich eine mehrstufige Adsorptionsanlage erfordern würde. Ferner bedarf es dann der Entsorgung großer Mengen der kontaminierten Aktivkohle.The adsorption of aromatic, heteroaromatic and aliphatic halogen compounds contained in highly polluted wastewater or leachate to activated carbon can only be regarded as a post-treatment stage, since direct use would require an extremely high amount of use and, in addition, a multi-stage adsorption system. Furthermore, it is then necessary to dispose of large quantities of the contaminated activated carbon.
Bekannt ist auch, Schadstoffe aus Abwässern durch Flockung bzw. Fällung unter Verwendung von insbesondere Verbindungen des dreiwertigen Eisens und Bildung von Eisen(III)-hydroxokomplexen zu eliminieren. Die Schadstoffe werden in der Flocke zum Teil eingeschlossen und/oder adsorptiv und/oder in Form von Fe-Komplexen chemisch gebunden und damit abtrennbar gemacht. So lassen sich beispielsweise zwar die CSB- und BSB-Werte von Sickerwässern absenken, jedoch wird eine Kombination mit einer Absorption an Aktivkohle für erforderlich gehalten - vgl. H.-J. Ehrig in "Deponie: Ablagerung von Abfällen / K.J. Thomé-Kozmiensky" (1987), Seiten 560-579. Um den organischen Halogengehalt auf Werte unter 1 mg Cl/l Wasser abzusenken, bedurfte es der Anwendung einer Flockungsfällung mit Eisen(III)-chlorid gefolgt von einer Aktivkohlebehandlung - vgl. A. Denne und E. Ecker in "Altlasten / K.J. Thomé-Kozmiensky" (1987), Seiten 649-656.It is also known to eliminate pollutants from waste water by flocculation or precipitation using, in particular, compounds of trivalent iron and the formation of iron (III) hydroxo complexes. The pollutants are partially enclosed in the flake and / or adsorptively and / or chemically bound in the form of Fe complexes and thus made separable. For example, the COD and BOD values of leachate can be reduced, but a combination with absorption of activated carbon is considered necessary - cf. H.-J. Ehrig in "Landfill: waste disposal / KJ Thomé-Kozmiensky" (1987), pages 560-579. In order to reduce the organic halogen content to values below 1 mg Cl / l water, flocculation with iron (III) chloride followed by an activated carbon treatment was required - cf. A. Denne and E. Ecker in "Altlasten / KJ Thomé-Kozmiensky" (1987), pages 649-656.
Zur Behandlung von Sickerwasser mit biologisch schwer abbaubaren chlororganischen Verbindungen wurde auch eine Oxidation mit Wasserstoffperoxid in Gegenwart einer katalytischen Menge Fe²⁺ erprobt - vgl. E. Gilbert und F. Bauer, Kernforschungszentrum Karlsruhe, KfK 4030, Febr. 1986. Bei einem pH-Wert unter 5 läßt sich bei einer H₂O₂-Dosis von 1 g H₂O₂ je g chemischen Sauerstoffbedarf (CSB) und einem H₂O₂/Fe²⁺-Molverhältnis von 10:1 (Fentons Reagenz) und einer Reaktionszeit um eine Stunde ein großer Teil der organischen Schadstoffe abbauen. Unter diesen Bedingungen konnte aber der AOX-Wert als Maß für halogenorganische Schadstoffe zwar reduziert, aber bei weitem nicht unter 1 mg/l gesenkt werden. Wird nach der Oxidation der pH-Wert auf 7-8 eingestellt, fallen Eisen(III)-hydroxokomplexe (=Eisen(III)-oxidhydrat) aus, welche einen Teil des organischen Kohlenstoffs adsorbiert und eingeschlossen enthalten: dies ändert aber das Bild bezüglich des Restgehalts an chlororganischen Schadstoffen im behandelten Wasser nur wenig, und auch durch eine nachgeschaltete biologische Reinigungsstufe konnte der AOX-Wert nur um insgesamt 92 % reduziert werden.For the treatment of leachate with biodegradable organochlorine compounds, oxidation with hydrogen peroxide in the presence of a catalytic amount of Fe²⁺ was also tested - cf. E. Gilbert and F. Bauer, Nuclear Research Center Karlsruhe, KfK 4030, February 1986. At a pH value below 5, an H₂O₂ dose of 1 g H₂O₂ per g chemical oxygen demand (COD) and an H₂O₂ / Fe²⁺- Molar ratio of 10: 1 (Fenton's reagent) and a reaction time of one hour break down a large part of the organic pollutants. Under these conditions, however, the AOX value as a measure of organohalogen pollutants could be reduced, but by no means lower than 1 mg / l. If the pH is adjusted to 7-8 after the oxidation, iron (III) hydroxo complexes (= iron (III) oxide hydrate) precipitate, which adsorb and contain part of the organic carbon: this changes the picture with respect to the Residual content of organochlorine pollutants in the treated water only a little, and the AOX value could only be reduced by a total of 92% through a subsequent biological purification stage.
Die Aufgabe der Erfindung besteht darin, ein Verfahren zur Abtrennung von halogenorganischen Schadstoffen mit mindestens 5 C-Atomen aus Wasser, das zusätzlich andere organische und/oder anorganische Schadstoffe enthalten kann, aufzuzeigen, das es gestattet, einstufig und leicht steuerbar die genannten halogenorganischen Schadstoffe durch Adsorption an in situ gebildeten Eisen(III)-hydroxokomplexen bis auf Restwerte von unter 1 mg/l, berechnet als organisch gebundenes Halogen, abzutrennen. Das Verfahren sollte mit einem möglichst niedrigen Einsatz an Chemikalien und geringem Anfall an kontaminierten Produkten auch dann zuverlässig betrieben werden können, wenn der Gehalt an Schadstoffen im zu behandelnden Wasser stark schwankt.The object of the invention is to provide a process for the separation of organohalogen pollutants with at least 5 carbon atoms from water, which may additionally contain other organic and / or inorganic pollutants, which allows the aforementioned organohalogen pollutants to be controlled in a simple and easy manner Separate adsorption on in situ formed iron (III) hydroxo complexes down to residual values of less than 1 mg / l, calculated as organically bound halogen. The process should be able to be operated reliably with the lowest possible use of chemicals and a low amount of contaminated products even if the content of pollutants in the water to be treated fluctuates greatly.
Die Aufgabe wird gelöst durch ein Verfahren zur Abtrennung von halogenorganischen Schadstoffen mit mindestens 5 C-Atomen aus Wasser, das zusätzlich andere organische und/oder anorganische Schadstoffe enthalten kann, auf Restwerte unter 1 mg/l, berechnet als organisch gebundenes Halogen, durch Adsorption der halogenorganischen Schadstoffe an in situ durch Hydrolyse von Eisen(III)-salzen gebildeten Eisen(III)-hydroxokomplexen und Abtrennung derselben in flockiger Form bei pH 5 bis 10, das dadurch gekennzeichnet ist, daß man im Wasser den Gehalt an Fe²⁺ bestimmt und, soweit erforderlich, durch Zugabe eines Eisen(II)-salzes einen Gehalt von 20 bis 1000 mg Fe²⁺ pro l Wasser einstellt und anschließend ein Oxidationsmittel zur Überführung von Fe²⁺ in Fe³⁺ in einer Menge zugibt, die jene nicht überschreitet, welche zur Oxidation von mindestens 20 mg Fe²⁺/l und maximal 1000 mg der anwesenden Menge Fe²⁺/l in Gegenwart von ggf. anwesenden, wie Fe²⁺ praktisch augenblicklich oxidierbaren anderen Bestandteilen erforderlich ist.The object is achieved by a process for separating organohalogen pollutants with at least 5 carbon atoms from water, which may additionally contain other organic and / or inorganic pollutants, to residual values below 1 mg / l, calculated as organically bound halogen, by adsorption of the organohalogen pollutants on iron (III) hydroxo complexes formed in situ by hydrolysis of iron (III) salts and separation thereof in flocculent form at pH 5 to 10, which is characterized in that the Fe²⁺ content in the water is determined and if necessary, by adding an iron (II) salt to a content of 20 to 1000 mg Fe²⁺ per l of water and then adding an oxidizing agent for converting Fe²⁺ in Fe³⁺ in an amount that does not exceed those for oxidation of at least 20 mg Fe²⁺ / l and a maximum of 1000 mg of the amount Fe²⁺ / l present in the presence of any present, such as Fe²⁺ practically instantaneously Lich oxidizable other ingredients is required.
Die Unteransprüche richten sich auf bevorzugte Ausführungsformen des Verfahrens.The subclaims are directed to preferred embodiments of the method.
Bei dem erfindungsgemäß zu behandelnden Wasser kann es sich um Wasser unterschiedlicher Provenienz handeln, etwa um Prozeßwasser, Abwasser oder, besonders bevorzugt, um Deponiesickerwasser und kontaminiertes Grundwasser. Nach der Behandlung kann das Wasser, soweit erforderlich, einer biologischen Kläranlage zugeleitet werden. Der im Verfahren anfallende Schlamm aus Eisen(III)-hydroxokomplexen, auch als Eisen(III)-oxidhydrat bezeichnet, enthält nicht nur die aus dem Wasser abgetrennten halogenorganischen Schadstoffe mit mindestens 5 C-Atomen, sondern er kann auch eine Reihe anderer Inhaltsstoffe des Wassers, wie z. B. Eisen-Huminsäure-Komplexe und Schwermetallcyanide im Falle eines Deponiesickerwassers, enthalten. Erfindungsgemäß gelingt es somit, nicht nur die anspruchsgemäßen Schadstoffe abzutrennen, sondern gleichzeitig werden die anspruchsgemäßen Schadstoffe abzutrennen, sondern gleichzeitig werden auch der CSB-Wert (=Chemischer Sauerstoff-Bedarf) und ggf. Schadmetallgehalt erniedrigt.The water to be treated according to the invention can be water of different provenances, for example process water, waste water or, particularly preferably, landfill leachate and contaminated groundwater. After treatment, the water can, if necessary, be sent to a biological treatment plant. The resulting sludge from iron (III) hydroxo complexes, also known as iron (III) oxide hydrate, not only contains the halogen-organic pollutants separated from the water with at least 5 C atoms, but it can also contain a number of other water components , such as B. iron-humic acid complexes and heavy metal cyanides in the case of landfill leachate. According to the invention, it is therefore not only successful Separate pollutants, but at the same time separate the demanding pollutants, but at the same time the COD value (= chemical oxygen demand) and possibly harmful metal content are reduced.
Bei den abzutrennenden halogenorganischen Schadstoffen mit mindestens 5 C-Atomen handelt es sich insbesondere um solche aus der Gruppe der polychlorierten Biphenylene (PCB's), polychlorierter Dibenzodioxine und Dibenzofurane, polychlorierter Benzole, Chlorphenole, halogenhaltiger Pestizide und aliphatischer und cycloaliphatischer Chlorkohlenwasserstoffe mit mindestens 5 C-Atomen. Besonders geeignet ist das Verfahren zur Abtrennung der sogenannten PCB's einschließlich der oben genannten Dioxine und Furane und aromatischen Verbindungen. Der Restwert von unter 1 mg/l bezieht sich auf das organisch gebundene Chlor der halogenorganischen Schadstoffe mit mehr als 5 C-Atomen. Halogenorganische Verbindungen mit 1 bis 4 C-Atomen, wie Halogenalkane und -alkene, werden im erfindungsgemäßen Verfahren nicht oder unvollständig aus dem Wasser abgetrennt. Das erfindungsgemäße Verfahren läßt sich somit besonders dort vorteilhaft einsetzen, wo das Wasser keine halogenorganischen Schadstoffe mit 1 bis 4 C-Atomen enthält oder deren Abtrennung nicht erforderlich ist. Vorzugsweise wird das erfindungsgemäße Verfahren so betrieben, daß der Restgehalt an organisch gebundenem Chlor bei Abwesenheit von halogenorganischen C₁-C₄-Verbindungen im zu behandelnden Wasser unter 0,2 mg/l und besonders bevorzugt unter 0,1 mg/l liegt.The halogen-organic pollutants to be separated with at least 5 C atoms are in particular those from the group of polychlorinated biphenylenes (PCB's), polychlorinated dibenzodioxins and dibenzofurans, polychlorinated benzenes, chlorophenols, halogen-containing pesticides and aliphatic and cycloaliphatic chlorinated hydrocarbons with at least 5 C atoms . The process is particularly suitable for separating the so-called PCBs, including the above-mentioned dioxins and furans and aromatic compounds. The residual value of less than 1 mg / l refers to the organically bound chlorine of the halogen-organic pollutants with more than 5 carbon atoms. Organohalogen compounds with 1 to 4 carbon atoms, such as haloalkanes and alkenes, are not or only incompletely separated from the water in the process according to the invention. The process according to the invention can thus be used particularly advantageously where the water contains no halogen-organic pollutants with 1 to 4 carbon atoms or where it is not necessary to separate them. The process according to the invention is preferably operated such that the residual content of organically bound chlorine in the absence of organo-halogenated C₁-C₄ compounds in the water to be treated is below 0.2 mg / l and particularly preferably below 0.1 mg / l.
Die Flockung bzw. Fällung von in situ durch Hydrolyse von Eisen(III)-verbindungen gebildeten Eisen(III)-hydroxokomplexen, welche kolloide und in wechselndem Umfang gelöste Bestandteile im Wasser durch Adsorption und/oder Einschluß abzutrennen gestattet, ist in der Abwassertechnik ein bekannter und auch praktizierter Verfahrensschritt. Üblicherweise wird dem Wasser eine lösliche Eisen(III)-verbindung zugegeben, und oberhalb eines pH-Wertes von etwa 3,5 beginnt die Ausfällung, welche bei pH 5 praktisch quantitativ ist. Zur Ausbildung eines leichter durch Schwerkraft abtrennbaren und entwässerbaren Niederschlags wird häufig ein pH-Wert oberhalb 7 eingestellt. Es wurde gefunden, daß durch diese Flockung in gewissem Umfang auch die anspruchsgemäßen Schadstoffe abtrennbar sind, Restwerte unter 1 mg/l organisch gebundenes Halogen hiermit aber nicht erreichbar sind. Es war somit überraschend, daß durch Zugabe eines Oxidationsmittels zu einem Wasser, das 20 bis 1000 mg Fe²⁺/l enthält, in situ solche Eisen(III)-hydroxokomplexe gebildet werden, welche die anspruchsgemäßen Schadstoffe praktisch quantitativ adsorbieren oder in anderer Weise binden und bei pH 5 bis 10 abgetrennt werden können.Flocculation or precipitation of iron (III) -hydroxo complexes formed in situ by hydrolysis of iron (III) compounds, which allows colloidal and to a varying extent dissolved components in water to be separated off by adsorption and / or inclusion, is in wastewater technology a well-known and also practiced process step. A soluble iron (III) compound is usually added to the water, and above a pH of about 3.5 the precipitation begins, which is practically quantitative at pH 5. A pH value above 7 is often set in order to form a precipitation that is easier to separate and drain by gravity. It was found that the flocculation to a certain extent enables the pollutants claimed to be separated off, but that residual values below 1 mg / l of organically bound halogen cannot be achieved with them. It was therefore surprising that by adding an oxidizing agent to a water containing 20 to 1000 mg Fe²⁺ / l, in situ those iron (III) hydroxo complexes are formed which practically quantitatively adsorb or otherwise bind the demanding pollutants and can be separated at pH 5 to 10.
Das zu behandelnde Wasser soll einen Gehalt von 20 bis 1000 mg Fe²⁺/l, vorzugsweise 50 bis 500 mg/g und besonders bevorzugt 100 bis 200 mg/g enthalten. Dieser Fe²⁺-Gehalt kann ganz oder teilweise bereits in dem zu behandelnden Wasser vorliegen oder durch Zugabe einer löslichen Eisen(II)-verbindung, vorzugsweise FeSO₄ · 7 H₂O oder FeCl₂, eingestellt werden. Üblicherweise wird man die Eisen(II)-verbindung als wäßrige Lösung einsetzen, da hiermit eine einfache Dosierung, wie sie für ein z. B. elektrometrisch gesteuertes kontinuierliches Verfahren zwingend ist, gewährleistet ist. Prinzipiell kann der FeCl₂-Gehalt auch über 1000 mg/l liegen, jedoch ist dies im Hinblick auf das daraus resultierende Schlammvolumen weniger empfehlenswert und zum Zweck der Abtrennung der halogenorganischen Schadstoffe nicht erforderlich. Im Falle sehr geringer Fe²⁺-Gehalte kann es vorteilhaft sein, nach der erfindungsgemäßen Oxidation und, soweit erforderlich, pH-Einstellung ein polymeres Flockungshilfsmittel zur Verbesserung der Flockung und leichteren Abtrennung des Niederschlags zuzusetzen.The water to be treated should contain 20 to 1000 mg Fe² mg / l, preferably 50 to 500 mg / g and particularly preferably 100 to 200 mg / g. This Fe²⁺ content can be present in whole or in part in the water to be treated or can be adjusted by adding a soluble iron (II) compound, preferably FeSO₄ · 7 H₂O or FeCl₂. Usually you will use the iron (II) compound as an aqueous solution, since this is a simple dosage, as for a z. B. electrometrically controlled continuous process is guaranteed. In principle, the FeCl₂ content can also be over 1000 mg / l, but this is less recommendable in view of the resulting sludge volume and is not necessary for the purpose of separating the halogen-organic pollutants. In the case of very low Fe 2 O contents, it can be advantageous to add a polymeric flocculant to improve the flocculation and to separate the precipitate more easily after the oxidation according to the invention and, if necessary, pH adjustment.
Zur Oxidation des Fe²⁺ zu Fe³⁺ wird dem Fe²⁺ enthaltenden Wasser eine ausreichende Menge Oxidationsmittel zugegeben. Es ist ein Kennzeichen des Verfahrens, daß die Oxidationsmittelmenge so bemessen wird, daß damit mindestens 20 mg Fe²⁺/l bis maximal der anwesenden Menge Fe²⁺/l, also maximal 1000 mg Fe²⁺/l, in Gegenwart von ggf. anwesenden, wie Fe²⁺ praktisch augenblicklich oxidierbaren anderen organischen und/oder anorganischen Inhaltsstoffen des zu behandelnden Wassers oxidiert werden. Vorzugsweise oxidiert man im wesentlichen die gesamte anwesende Menge Fe²⁺. Es steht somit kein Oxidationsmittel zum oxidativen Angriff von C-Atomen zur Verfügung. Die vorbekannte oxidative Behandlung von Deponiesickerwasser unter Verwendung von Fentons Reagenz erforderte stets einen vielfachen Überschuß des Oxidationsmittels gegenüber Fe²⁺, ohne daß die halogenorganischen Schadstoffe ausreichend abgebaut und abgetrennt werden konnten. Unter den ebenso leicht wie Fe²⁺ oxidierbaren Stoffen sind solche zu verstehen, welche mit dem Fe²⁺ unter den Betriebsbedingungen - im allgemeinen 5-25 °C - nennenswert um das zugegebene Oxidationsmittel konkurrieren; hierzu gehören beispielsweise organische und anorganische Sulfide, Sulfite.A sufficient amount of oxidizing agent is added to the water containing Fe²⁺ for the oxidation of Fe²⁺ to Fe³⁺. It is a characteristic of the process that the amount of oxidizing agent is dimensioned so that at least 20 mg Fe²⁺ / l up to a maximum of the amount of Fe²⁺ / l present, i.e. a maximum of 1000 mg Fe²⁺ / l, in the presence of any present, such as Fe²⁺ can be oxidized practically instantaneously oxidizable other organic and / or inorganic ingredients of the water to be treated. Preferably, essentially the entire amount of Fe²⁺ present is oxidized. There is therefore no oxidizing agent available for the oxidative attack of carbon atoms. The previously known oxidative treatment of landfill leachate using Fenton's reagent always required a multiple excess of the oxidizing agent over Fe²⁺ without the halogen-organic pollutants being able to be sufficiently broken down and separated off. Substances that are as easy to oxidize as Fe²⁺ are understood to mean those which compete appreciably with Fe²⁺ under the operating conditions - generally 5-25 ° C - for the oxidizing agent added; these include, for example, organic and inorganic sulfides, sulfites.
Als Oxidationsmittel können im Prinzip solche verwendet werden, welche ein höheres Oxidationspotential als Fe³⁺ haben, jedoch kommen in der Praxis nur solche in Betracht, welche dem Wasser keine neuen Schadstoffe zufügen. Chlor, Hypochlorit und Chlordioxid können verwendet werden, sind aber wegen der damit einhergehenden Aufsalzung und des sicherheitstechnischen Aufwands weniger empfehlenswert. Sauerstoff als Oxidationsmittel hat den Nachteil, daß es bei der Behandlung von stark kontaminiertem Wasser, wie Deponiesickerwasser, zu erheblichen Geruchsemissionen kommen kann. Eine Ozonisierung ist möglich, im Regelfall aber wenig wirtschaftlich. Bevorzugt werden anorganische Aktivsauerstoffverbindungen, wie insbesondere Wasserstoffperoxid, Perschwefelsäure, Persulfate, Natriumpercarbonat, Natriumperborate. Ganz besonders bevorzugt wird Wasserstoffperoxid in Form handelsüblicher wäßriger Lösungen mit einem Gehalt von 30 - 85 Gew.-%, soweit erwünscht, können auch verdünntere als 30 gew.-%ige Lösungen eingesetzt werden.In principle, those which have a higher oxidation potential than Fe³⁺ can be used as oxidizing agents, but in practice only those are considered which do not add any new pollutants to the water. Chlorine, hypochlorite and chlorine dioxide can be used, but are less recommendable due to the associated salting and the safety-related effort. Oxygen as an oxidizing agent has the disadvantage that it can lead to considerable odor emissions when treating heavily contaminated water, such as landfill leachate. Ozonation is possible, but is usually not very economical. Inorganic are preferred Active oxygen compounds, such as in particular hydrogen peroxide, persulfuric acid, persulfates, sodium percarbonate, sodium perborates. Hydrogen peroxide is very particularly preferred in the form of commercially available aqueous solutions with a content of 30-85% by weight, if desired, solutions which are more dilute than 30% by weight can also be used.
Das erfindungsgemäße Verfahren läßt sich durch Messung des Fe²⁺/Fe³⁺-Redoxpotentials sehr einfach steuern. Das Fe²⁺/Fe³⁺-Redoxpotential, das sich in an sich bekannter Weise z. B. unter Verwendung einer Edelmetallelektrode und einer Bezugselektrode, messen läßt, kann sowohl zur Bestimmung des Fe²⁺-Gehalts als auch zur Dosierung des Oxidationsmittels herangezogen werden, da bei vollständiger Überführung des Fe²⁺ in Fe³⁺ ein praktisch konstanter Potentialwert von +970 bis +980 mV (Pt/Thalamid-Elektrodenkette) erreicht wird. Unter Verwendung der genannten Elektrodenkette entspricht ein Potential von +450 mV etwa 1000 mg Fe²⁺/l und ein Potentialwert von +600 mV etwa 70 mg Fe²⁺/l - gemessen bei pH 7,2. Für die Aussteuerung der Dosiereinrichtung für die bedarfsgerechte Zugabe der Fe²⁺-salzlösung kann ein Redox-Regler mit P- (=Proportional), PI- (=Proportional-Integral) oder PID- (=Proportional-Integral-Digital) Verhalten eingesetzt werden; auch der Einsatz der SP-Steuerung (speicherprogrammierbar) ist möglich. Die Dosierpumpe für das Oxidationsmittel wird automatisch abgeschaltet, wenn der vorgegebene Endpotentialwert erreicht ist.The inventive method can be controlled very easily by measuring the Fe²⁺ / Fe³⁺ redox potential. The Fe²⁺ / Fe³⁺ redox potential, which z. B. using a noble metal electrode and a reference electrode, can be used to determine both the Fe²⁺ content and the dosage of the oxidizing agent, since with complete conversion of Fe²⁺ to Fe³⁺ a practically constant potential value of +970 to + 980 mV (Pt / thalamide electrode chain) is reached. Using the electrode chain mentioned, a potential of +450 mV corresponds to approximately 1000 mg Fe²⁺ / l and a potential value of +600 mV corresponds to approximately 70 mg Fe²⁺ / l - measured at pH 7.2. A redox controller with P- (= proportional), PI- (= proportional-integral) or PID (= proportional-integral-digital) behavior can be used to control the metering device for the needs-based addition of the Fe²⁺ salt solution; it is also possible to use the SP control (programmable logic controller). The dosing pump for the oxidizing agent is automatically switched off when the specified end potential value is reached.
Der pH-Wert des zu behandelnden Wassers kann zu Beginn im schwach sauren bis schwach alkalischen Bereich, etwa pH 5-9, liegen. Während der Oxidation sinkt der pH-Wert je nach dem Gehalt an Fe²⁺ als auch dem Puffervermögen des Wassers ab. Sofern nach der Zugabe des Oxidationsmittels der pH-Wert unter 5 abgesunken ist, wird die meist während der Oxidationsmittelzugabe beginnende Ausfällung von Fe(III)- hydroxokomplexen durch anschließende Zugabe einer alkalisch wirkenden Alkali- oder Erdalkaliverbindung vervollständigt.The pH of the water to be treated can initially be in the slightly acidic to weakly alkaline range, about pH 5-9. During the oxidation, the pH value drops depending on the Fe²⁺ content and the buffering capacity of the water. If the pH value drops below 5 after the addition of the oxidizing agent, the precipitation of Fe (III) - which usually begins during the addition of the oxidizing agent - hydroxo complexes completed by the subsequent addition of an alkaline alkali or alkaline earth compound.
Wie bereits ausgeführt, wird der die adsorbierten halogenierten und ggf. andere Schadstoffe enthaltende Niederschlag bei pH 5-10, vorzugsweise 7,5-9, vom Wasser abgetrennt. Zur Abtrennung sind gängige Vorrichtungen, wie Eindicker, Separatoren, Zentrifugen, Filterpressen, einsetzbar. Der abgetrennte Niederschlag, der die Schadstoffe enthält, kann einer Verbrennungsanlage zugeführt werden. Durch das erfindungsgemäße Verfahren lassen sich mittels einfacher Maßnahmen und mit geringem Chemikalienaufwand und gleichzeitig sicher steuerbar sehr niedrige Restwerte an organisch gebundenem Chlor aus Schadstoffen mit mindestens 5 C-Atomen erzielen.As already stated, the precipitate containing the adsorbed halogenated and possibly other pollutants is separated from the water at pH 5-10, preferably 7.5-9. Common devices such as thickeners, separators, centrifuges, filter presses can be used for the separation. The separated precipitate, which contains the pollutants, can be fed to an incineration plant. By means of the method according to the invention, very low residual values of organically bound chlorine from pollutants with at least 5 C atoms can be achieved by means of simple measures and with little expenditure on chemicals and at the same time in a controllable manner.
Die Erfindung wird an den nachfolgenden Beispielen verdeutlicht.The invention is illustrated by the following examples.
Deponiesickerwässer und Grundwässer fallen meist in einem pH-Bereich von 6,5 bis 7,5 an. Bei diesem pH-Wert liegt das darin gelöste bzw. zugegebene Fe²⁺ in gelöster Form vor, so daß mittels eines zuvor erstellten Diagramms die Konzentration in Abhängigkeit vom gemessenen Redoxpotential bestimmt werden kann.Landfill leachate and groundwater usually occur in a pH range of 6.5 to 7.5. At this pH, the Fe² gel dissolved or added therein is in dissolved form, so that the concentration can be determined as a function of the measured redox potential using a previously created diagram.
Zu 5 l eines Deponiesickerwassers mit einem Gehalt von 50 ppb PCB, einem pH-Wert von 6,8 und einem Redoxpotential von +750 mV, gemessen mit einer Pt/Thalamid-Elektrodenkette (Thalamid ist eine Bezugselektrode der Firma Schott & Sen., Mainz) wurde eine 5 gew.-%ige wäßrige FeSO₄-Lösung bis zu einem Redoxpotential von 580 mV, entsprechend 100 mg Fe²⁺/l, zugegeben. Im Anschluß wurde unter Rühren eine 5 gew.-%ige wäßrige H₂O₂-Lösung bis zu einem Potential von +970 mV zudosiert. Nach Einstellung eines pH-Wertes von 8,5 durch Zugabe von Natronlauge wurde filtriert. Der Restgehalt an PCB im behandelten Wasser betrug unter 1 ppb - die PCB-Bestimmung erfolgte durch gaschromatographische Bestimmung eines Extraktes.To 5 l of landfill leachate with a content of 50 ppb PCB, a pH of 6.8 and a redox potential of +750 mV, measured with a Pt / Thalamid electrode chain (Thalamid is a reference electrode from Schott & Sen., Mainz ) was a 5 wt .-% aqueous FeSO₄ solution up to a redox potential of 580 mV, corresponding to 100 mg Fe²⁺ / l, admitted. A 5% by weight aqueous H₂O₂ solution was then metered in with stirring to a potential of +970 mV. After the pH had been adjusted to 8.5 by adding sodium hydroxide solution, the mixture was filtered. The residual PCB content in the treated water was less than 1 ppb - the PCB was determined by gas chromatographic determination of an extract.
Zu entgiften war ein Wasser, das 10 mg Clophen/l (=PCB) und organische Lösungsvermittler enthielt.
- a) Das Wasser wurde erfindungsgemäß behandelt, indem 100 mg Fe²⁺ zugegeben und dann redoxgesteuert mit Wasserstoffperoxid oxidiert wurde; der pH-Wert wurde mit NaOH auf 8,5 eingestellt, anschließend wurde filtriert. Im Filtrat wurde ein Restgehalt von unter 1 µg Clophen/l analysiert.
- b) Zum Vergleich wurde das gleiche Wasser mit 100 mg Fe³⁺ versetzt - Zugabe als Fe₂(SO₄)₃. Nach der Einstellung des pH-Wertes auf 8,5 wurde filtriert. Das Filtrat wies einen Restgehalt von 2,5 mg Clophen/l auf.
- a) The water was treated according to the invention by adding 100 mg Fe²⁺ and then redox-controlled with hydrogen peroxide; the pH was adjusted to 8.5 with NaOH and then filtered. A residual content of less than 1 µg clophen / l was analyzed in the filtrate.
- b) For comparison, the same water was mixed with 100 mg Fe³⁺ - addition as Fe₂ (SO₄) ₃. After adjusting the pH to 8.5, the mixture was filtered. The filtrate had a residual content of 2.5 mg clophen / l.
Claims (7)
dadurch gekennzeichnet,
daß man im Wasser den Gehalt an Fe²⁺ bestimmt und, soweit erforderlich, durch Zugabe eines Eisen(II)-salzes einen Gehalt von 20 bis 1000 mg Fe²⁺ pro l Wasser einstellt und anschließend ein Oxidationsmittel zur Überführung von Fe²⁺ in Fe³⁺ in einer Menge zugibt, die jene nicht überschreitet, welche zur Oxidation von mindestens 20 mg Fe²⁺/l und maximal 1000 mg der anwesenden menge Fe²⁺/l in Gegenwart von gegebenenfalls anwesenden, wie Fe²⁺ praktisch augenblicklich oxidierbaren anderen Bestandteilen erforderlich ist.1. Process for the separation of organohalogen pollutants with at least 5 carbon atoms from water, which may additionally contain other organic and / or inorganic pollutants, to residual values below 1 mg / l, calculated as organically bound halogen, by adsorption of the organohalogen pollutants onto in iron (III) hydroxo complexes formed by hydrolysis of iron (III) salts and separation thereof in flaky form at pH 5 to 10,
characterized,
that the water content of Fe²⁺ is determined and, if necessary, a content of 20 to 1000 mg of Fe²⁺ per l of water is adjusted by adding an iron (II) salt and then an oxidizing agent for converting Fe²⁺ into Fe³⁺ in admits an amount which does not exceed that which is necessary for the oxidation of at least 20 mg Fe²⁺ / l and a maximum of 1000 mg of the amount Fe²⁺ / l present in the presence of any present, such as Fe²⁺ practically instantaneously oxidizable other components.
dadurch gekennzeichnet,
daß es sich bei dem zu behandelnden Wasser um Deponiesickerwasser oder kontaminiertes Grundwasser mit einem Gehalt an halogenorganischen Schadstoffen aus der Gruppe polychlorierter Biphenylene (PCB's), polychlorierter Dibenzodioxine und Dibenzofurane, polychlorierter Benzole, Chlorphenole, halogenhaltiger Pestizide handelt.2. The method according to claim 1,
characterized,
that the water to be treated is landfill leachate or contaminated groundwater containing organohalogen pollutants from the group of polychlorinated biphenylenes (PCBs), polychlorinated dibenzodioxins and dibenzofurans, polychlorinated benzenes, chlorophenols, halogen-containing pesticides.
dadurch gekennzeichnet,
daß man halogenorganische Schadstoffe mit mindestens 5 C-Atomen bis auf Restwerte unter 0,2 mg/l, vorzugsweise unter 0,1 mg/l, abtrennt.3. The method according to claim 1 or 2,
characterized,
that one separates organohalogen pollutants with at least 5 carbon atoms down to residual values below 0.2 mg / l, preferably below 0.1 mg / l.
dadurch gekennzeichnet,
daß man als Oxidationsmittel eine anorganische Aktivsauerstoffverbindung, insbesondere Persulfate, Percarbonate oder besonders bevorzugt Wasserstoffperoxid, verwendet.4. The method according to one or more of claims 1 to 3,
characterized,
that an inorganic active oxygen compound, in particular persulfates, percarbonates or particularly preferably hydrogen peroxide, is used as the oxidizing agent.
dadurch gekennzeichnet,
daß man dem Wasser eine solche Menge eines Eisen(II)-salzes zugibt, daß der Gehalt 50 bis 400 mg Fe²⁺/l, vorzugsweise 100 bis 200 mg Fe²⁺/l, beträgt, und durch Zugabe des Oxidationsmittels im wesentlichen das gesamte anwesende Fe²⁺ in Fe³⁺ überführt.5. The method according to one or more of claims 1 to 4,
characterized,
that one adds an amount of an iron (II) salt to the water that the content is 50 to 400 mg Fe²⁺ / l, preferably 100 to 200 mg Fe²⁺ / l, and by adding the oxidizing agent essentially all that is present Fe²⁺ converted to Fe³⁺.
dadurch gekennzeichnet,
daß man das Eisen(II)-salz als auch das Oxidationsmittel in Form wäßriger Lösungen zum zu behandelnden Wasser zugibt und die Zugabemengen über die Messung des Fe²⁺/Fe³⁺-Redoxpotentials steuert.6. The method according to one or more of claims 1 to 5,
characterized,
that the iron (II) salt and the oxidizing agent are added in the form of aqueous solutions to the water to be treated and the addition amounts are controlled by measuring the Fe²⁺ / Fe³⁺ redox potential.
dadurch gekennzeichnet,
daß man unter Verwendung einer Platin/Thalamid-Elektrodenkette durch Zugabe einer wäßrigen Eisen(II)-salzlösung ein Redoxpotential im Bereich von +450 bis 600 mV einstellt und anschließend Wasserstoffperoxid als Oxidationsmittel in einer Menge zufügt, bis das Redoxpotential einen Wert von +980 mV annimmt.7. The method according to claim 6,
characterized,
that a redox potential in the range of +450 to 600 mV is set using a platinum / thalamide electrode chain by adding an aqueous iron (II) salt solution and then hydrogen peroxide is added as an oxidizing agent in an amount until the redox potential has a value of +980 mV assumes.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
AT90116049T ATE74883T1 (en) | 1989-09-27 | 1990-08-22 | PROCESS FOR THE SEPARATION OF ORGANIC HALOGENS WITH AT LEAST 5 C-ATOMS FROM WATER. |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
DE3932175 | 1989-09-27 | ||
DE3932175 | 1989-09-27 |
Publications (2)
Publication Number | Publication Date |
---|---|
EP0419842A1 true EP0419842A1 (en) | 1991-04-03 |
EP0419842B1 EP0419842B1 (en) | 1992-04-15 |
Family
ID=6390266
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP90116049A Expired - Lifetime EP0419842B1 (en) | 1989-09-27 | 1990-08-22 | Method for removing halogenated organic contaminants with at least 5 c-atoms from water |
Country Status (4)
Country | Link |
---|---|
EP (1) | EP0419842B1 (en) |
AT (1) | ATE74883T1 (en) |
DE (1) | DE59000089D1 (en) |
GR (1) | GR3004543T3 (en) |
Cited By (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0481269A2 (en) * | 1990-10-16 | 1992-04-22 | Hoelzle & Chelius GmbH | Water conditioning agent and/or water germicide without perborate or borate, method for its production and its use |
FR2689492A1 (en) * | 1992-04-03 | 1993-10-08 | Omnium Traitement Valorisa | Treating surface water contaminated with organic matter and micro-pollutants - by adding hydrogen peroxide and ferrous salt |
WO1994013591A1 (en) * | 1992-12-04 | 1994-06-23 | Kemira Oy | Process for treating waste water |
EP1243561A2 (en) * | 2001-03-23 | 2002-09-25 | Degussa AG | Method for treating polluted water using an iron(III) catalyst |
Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0022525A1 (en) * | 1979-07-11 | 1981-01-21 | Bayer Ag | Process for treating waste water |
EP0238731A2 (en) * | 1986-03-28 | 1987-09-30 | The Boeing Company | System for removing toxic organics and metals from manufacturing wastewater |
EP0277632A1 (en) * | 1987-02-07 | 1988-08-10 | BASF Aktiengesellschaft | Process for catalytically destroying organic and inorganic oxidisable compounds in water |
-
1990
- 1990-08-22 AT AT90116049T patent/ATE74883T1/en not_active IP Right Cessation
- 1990-08-22 DE DE9090116049T patent/DE59000089D1/en not_active Expired - Lifetime
- 1990-08-22 EP EP90116049A patent/EP0419842B1/en not_active Expired - Lifetime
-
1992
- 1992-05-08 GR GR920400885T patent/GR3004543T3/el unknown
Patent Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0022525A1 (en) * | 1979-07-11 | 1981-01-21 | Bayer Ag | Process for treating waste water |
EP0238731A2 (en) * | 1986-03-28 | 1987-09-30 | The Boeing Company | System for removing toxic organics and metals from manufacturing wastewater |
EP0277632A1 (en) * | 1987-02-07 | 1988-08-10 | BASF Aktiengesellschaft | Process for catalytically destroying organic and inorganic oxidisable compounds in water |
Non-Patent Citations (3)
Title |
---|
JOURNAL WATER POLLUTION CONTROL FEDERATION, Band 36, Nr. 9, September 1964, Seiten 1116-1128, Washington, DC, US; H.R. EISENHAUER: "Oxidation of phenolic wastes" * |
PATENT ABSTRACTS OF JAPAN, Band 10, Nr. 136 (C-347), 20. Mai 1985; & JP-A-60 261 590 (MURATA SANGYO) 24-12-1985 * |
WASSER - ABWASSER (GWF), Band 129, Nr. 7, Juli 1988, Seiten 484-491, München, DE; H. SCHWARZER: "Oxidative Abwasser-Reinigung mit Wasserstoffperoxid" * |
Cited By (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0481269A2 (en) * | 1990-10-16 | 1992-04-22 | Hoelzle & Chelius GmbH | Water conditioning agent and/or water germicide without perborate or borate, method for its production and its use |
EP0481269A3 (en) * | 1990-10-16 | 1993-12-15 | Hoelzle & Chelius Gmbh | Water conditioning agent and/or water germicide without perborate or borate, method for its production and its use |
FR2689492A1 (en) * | 1992-04-03 | 1993-10-08 | Omnium Traitement Valorisa | Treating surface water contaminated with organic matter and micro-pollutants - by adding hydrogen peroxide and ferrous salt |
WO1994013591A1 (en) * | 1992-12-04 | 1994-06-23 | Kemira Oy | Process for treating waste water |
US5611928A (en) * | 1992-12-04 | 1997-03-18 | Kemira Oy | Process for treating waste water |
EP1243561A2 (en) * | 2001-03-23 | 2002-09-25 | Degussa AG | Method for treating polluted water using an iron(III) catalyst |
EP1243561A3 (en) * | 2001-03-23 | 2004-04-28 | Degussa AG | Method for treating polluted water using an iron(III) catalyst |
Also Published As
Publication number | Publication date |
---|---|
ATE74883T1 (en) | 1992-05-15 |
DE59000089D1 (en) | 1992-05-21 |
GR3004543T3 (en) | 1993-04-28 |
EP0419842B1 (en) | 1992-04-15 |
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